The invention relates to novel chlorine-containing triphendioxazine compounds and to their use as pigments. The invention also relates to a particularly advantageous process for preparing these triphendioxazine compounds.
GB 2284427 A describes chlorine-containing, symmetrically disubstituted triphendioxazine compounds of the following general formula 
where the rings labeled A carry rings which are fused linearly or angularly and consist of radical members, inter alia, of the formulae xe2x80x94NR1xe2x80x94(CO)mxe2x80x94NHxe2x80x94 and xe2x80x94CR1xe2x95x90CHxe2x80x94COxe2x80x94NHxe2x80x94 wherein R1 is hydrogen, C1-4alkyl or phenyl, preferably hydrogen, methyl or ethyl; and m is 1 or 2.
The preparation process disclosed in GB 2284427 A starts from intermediates i.e. amino compounds, which are ortho-substituted by an alkoxy group and are obtainable only by way of a relatively complex synthesis. The pigments disclosed in GB 2284427 A are difficult to disperse and cannot easily be brought into pigment form.
It is an object of the present invention to provide new pigments possessing high fastness to solvents, migration and light, which have good thermal stabilities and a high tinting power and are also easily dispersible respectively easily to be brought into pigment form.
Another object of the present invention is to provide a process by which the novel pigments are obtainable and which starts from readily available intermediates.
These objects are achieved by the novel triphendioxazine compounds of the present invention and their use for preparing pigments, and by the process by which these novel triphendioxazine compounds are obtainable.
The present invention therefore provides, firstly, compounds of the general formula (I): 
in which the rings labeled A in positions 1,2-, 2,3- or 3,4- and 8,9-, 9,10- or 10,11- carry a linearly or angularly fused heterocyclic ring containing at least one nitrogen atom which is substituted or unsubstituted, with the proviso that compounds with only unsubstituted nitrogen atoms and symmetrically disubstituted compounds with C1-2alkyl and unsubstituted phenyl substituents are excluded. Examples of such fused heterocyclic rings are enumerated in GB 2284427 which is incorporated herein by reference and are illustrated as groups of formulae a) to o).
Preferred compounds of formula (I) are those with formulae (Ia), (IIa), (IIIa) and (IIIb) 
where R1, R2, R3 and R4, independently of one another, are hydrogen, a C1-8alkyl radical, a substituted or unsubstituted phenyl, benzyl, benzanilide or naphthyl radical, a substituted or unsubstituted C5-6cycloalkyl radical or a radical of the formula 
xe2x80x83with the proviso that in the case of symmetrically disubstituted compounds the definitions hydrogen, C1-2alkyl radical and unsubstituted phenyl radical are excluded.
In view of the fact that only compounds having hydrogen substituents are capable of building hydrogen bridges (which is believed to be necessary for the pigmentary properties), it is surprising that even tetrasubstituted compounds possess pigmentary properties.
The substituents R1, R2, R3 and R4, independently of one another, are preferably hydrogen, a methyl radical, an ethyl radical, an n- or i-propyl radical, an n-, i-, sec- or tert-butyl radical, a cyclohexyl radical, a substituted or unsubstituted benzanilide radical, a naphthyl radical, a radical of the formula (a) 
an unsubstituted phenyl radical, a phenyl radical substituted one or more times by radicals selected from the group consisting of halogen, preferably chlorine, nitro groups, phenyl radicals, C1-8alkyl radicals, preferably C1-4alkyl radicals, and C1-2alkoxy radicals, with the above mentioned proviso for symmetrically disubstituted compounds.
The above mentioned substituted phenyl radical in the definition of R1 to R4 is preferably selected from the group consisting of o-, m-, p-methyl-, ethyl-, methoxyphenyl, 2,4- and 3,5-dimethylphenyl, 2,5-dichloro-, dimethoxy-, diethoxy-phenyl, m-, p-nitrophenyl, 2,5-dichloro-, 2,5-diethoxy-4-nitrophenyl, 2-methoxy-4-nitrophenyl, 3-chloro4-methyl-, 3-chloro4-methoxyphenyl, p-ethoxyphenyl and the radical 
The above mentioned substituted benzanilide radical in the definition of R1 to R4 is preferably selected from the group consisting of radicals of the formulae (b) and (c) 
Preferred triphendioxazine compounds are those for which R2 and R4 are hydrogen and R1 is a methyl radical and R3 is an ethyl radical (asymmetrically disubstituted compound) or in which R1 and R3 are each a 4-methylphenyl or 4-methoxyphenyl radical (symmetrically disubstituted compounds).
Preferred symmetrically tetrasubstituted compounds are the tetramethyl-, tetraethyl-, tetrapropyl (n- or i-) and tetrabutyl (n-, i-, sec- or tert-)substituted compounds.
Preferred asymmetrically tetrasubstituted compounds are those for which the definitions of R1 and R2 are selected from the group consisting of the radicals methyl, ethyl, propyl (n- or i-) and butyl (n-, i-, sec- or tert-) and R3 and R4 can have any of the above definitions.
It has been found that even amino compounds which are not ortho-substituted are suitable as intermediates provided that the cyclization which follows the reaction with 2,3,5,6-tetrachlorobenzoquinone (chloranil) is carried out with manganese dioxide and concentrated sulphuric acid, e.g. from 80 to 100% strength, preferably from 90 to 95% strength. The process for preparing the novel compounds of the formula (I) is therefore also an object of the present invention. Following the reaction of 1 mol of chloranil with 2 mol of a compound of the general formula (IV) 
in which ring A carries a fused heterocyclic ring containing at least one nitrogen atom which is substituted or unsubstituted with the abovementioned proviso, there follows the characterizing process step of the cyclization conducted with manganese dioxide (MnO2) and concentrated sulphuric acid, e.g. from 80 to 100% strength, preferably from 90 to 95% strength.
Preferred intermediates of formula (IV) are those of formulae (XVI) to (XVIc) 
where R1 and R2 are as defined above.
The advantage of this process is that it is possible to start from the intermediates (XVI), (XVIa), (XVIb) and (XVIc) which, unlike the amino compounds which carry an alkoxy group in the ortho position, are relatively easy to obtain. For example, compounds of the formula (XVI) are obtainable by a process comprising the following steps:
In a first step, the reaction of 2,4-dinitrochlorobenzene (XI) with the corresponding primary amine, to give the N-substituted 2,4-dinitroaniline (XII) 
In a second step, the reduction of the compound of the formula XII, preferably with hydrated sodium hydrogen sulphide, to give the 1,2-diamine compound (XIII) 
In a third step, the cyclization of a compound of the formula (XIII), preferably with phosgene, chloroformimc ester or urea, to give the 1,3-dihydrobenzimidazol-2-one compound 
where R1 is as defined above.
The disubstituted intermediate required to prepare the tetrasubstituted triphendioxazine compounds is obtainable, for example, by N-alkylation of the compound of the formula (XIV) in which R1 is as defined above, preferably using dialkyl sulphate, alkyl bromide or alkyl iodide or, respectively, benzyl bromide or benzyl chloride, to give the compound of the formula (XV) 
In a further step, the nitro compound of the formula (XV) is reduced, preferably by the method of Bxc3xa9champ, to give the amino compound of the formula (XVI) 
where R1 and R2 are as defined above.
Compounds of the formula (XVIa) are obtainable, for example, by cyclizing the compound of the formula (XIII) with oxalic acid or oxalic ester.
Compounds of the formula (XVIb) (5-aminobenzoxazolones) are preferably prepared by a process comprising the following steps: 
Compounds of the formula (XVIc) (6-aminobenzoxazolones) are obtainable, for example, by a process comprising the following steps: 
Compounds with angularly fused rings can be produced by similar methods using starting compounds having isomeric substitution, e.g. 3,4-dinitroaniline instead of 2,4-dinitroaniline.
Furthermore, there is also a process for preparing compounds of the formula (I) 
in which the rings labeled A in positions 1,2-, 2,3- or 3,4- and 8,9-, 9,10- or 10,11- carry a single chain linkage linking such positions, the single chain linkage having a formula selected from xe2x80x94NR5xe2x80x94(CO)mxe2x80x94NHxe2x80x94, xe2x80x94CR5xe2x95x90CHxe2x80x94COxe2x80x94NH, xe2x80x94COxe2x80x94CH2xe2x80x94COxe2x80x94NH, xe2x80x94COxe2x80x94CHxe2x95x90CR5xe2x80x94NH, xe2x80x94COxe2x80x94NHxe2x80x94COxe2x80x94NH, xe2x80x94COxe2x80x94NHxe2x80x94CR6xe2x95x90N, xe2x80x94CR6xe2x95x90Nxe2x80x94COxe2x80x94NH, xe2x80x94NR5xe2x80x94(CO)mxe2x80x94O or xe2x80x94NHxe2x80x94CR5xe2x95x90Nxe2x80x94,
wherein R5 is hydrogen, C1-4alkyl or phenyl; R6 is hydrogen, C1-4alkyl or phenyl; and m is 1 or 2. The process comprises reacting two moles of a compound of formula IV 
xe2x80x83in which ring A carries in two corresponding positions the single chain as defined above, with one mole of 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil) 
and cyclizing the compound of formula XVII to the compound of the formula I in the presence of manganese dioxide and concentrated sulphuric acid. More specifically, compounds of formula (IV) are represented by the formulae (IVa), (IVb) and (IVc) 
xe2x80x83in which X stands for the single chain linkage having a formula selected from xe2x80x94NR5xe2x80x94(CO)mxe2x80x94NHxe2x80x94, xe2x80x94CR5xe2x95x90CHxe2x80x94COxe2x80x94NH, xe2x80x94COxe2x80x94CH2xe2x80x94COxe2x80x94NH, xe2x80x94COxe2x80x94CHxe2x95x90CR5xe2x80x94NH, xe2x80x94COxe2x80x94NHxe2x80x94COxe2x80x94NH, xe2x80x94COxe2x80x94NHxe2x80x94CR6xe2x95x90N, xe2x80x94CR6xe2x95x90Nxe2x80x94COxe2x80x94NH, xe2x80x94NR5xe2x80x94(CO)mxe2x80x94O or xe2x80x94NHxe2x80x94CR5xe2x95x90Nxe2x80x94, wherein R5 is hydrogen, C1-4alkyl or phenyl; R6 is hydrogen, C1-4alkyl or phenyl; and m is 1 or 2.
Note that structures IVa and IVb are identical.
Furthermore, there is also the process for preparing a triphendioxazine compound of formulae (Ia), (IIa), (IIIa) or (IIIb) 
or 
wherein R1, R2, R3, and R4, independently of one another are, are hydrogen, a C1-8 alkyl radical, a substituted or unsubstituted phenyl, benzyl, benzanilide or naphthyl radical, a substituted or unsubstituted C5-6 cycloalkyl radical or a radical of formula (a) 
xe2x80x83provided that in a symmetrically disubstituted compound the definitions hydrogen, C1-2alkyl radical or unsubstituted phenyl radical are excluded. The process comprises reacting two moles of a compound of formulae (XVI), (XVIa), (XVIb) or (XVIc) 
xe2x80x83or 
xe2x80x83or 
xe2x80x83or 
with one mole of 2,3,5,6-tetrachloro-1,4-benzoquinone and cyclizing the obtained compounds of formulae (XVIIa), (XVIIb), (XVIIc) or (XVIId) 
in the presence of manganese dioxide and concentrated sulphuric acid.
Triphendioxazine compounds of the formula (I) according to the invention are used as pigments.
Aftertreating the crude pigments in organic solvents in which the pigments themselves are not dissolved and at elevated temperatures, for example at from 60 to 200xc2x0 C., especially from 70 to 150xc2x0 C. and preferably from 75 to 100xc2x0 C., can often be used to further improve the pigment properties. Aftertreatment is preferably combined with a milling or kneading operation.
The pigments according to the invention are excellently suited to the colouring of polymer compositions, by which are meant solvent-free and solvent-containing compositions comprising plastics or synthetic resins (in oil-based or water-based paints, in coating materials of various kinds, for the spin dyeing of viscose or cellulose acetate, or for pigmenting plastics, such as polyamide, polyethylene, polystyrene, polyvinyl chloride, rubber and artificial leather). They can also be used in printing inks for the graphical industry, for the colouring of paper pulps, for the coating of textile or for pigment printing.
The resulting colorations are notable for their outstanding heat, light and weather fastness, chemical resistance, colour strength and very good applications properties, examples being their crystallization fastness and dispersing fastness, and especially for their fastness to migration, bleeding, overcoating and solvents.
In addition, the pigments of the invention are also suitable as colorants in electrophotographic toners and developers, such as one- or two-component powder toners (also known as one- or two-component developers), magnetic toners, liquid toners, polymerization toners and further speciality toners (literature: L. B. Schein, xe2x80x9cElectrophotography and Development Physicsxe2x80x9d; Springer Series in Electrophysics 14, Springer Verlag, 2nd edition, 1992).
Typical toner binders are addition polymerization, polyaddition and polycondensation resins, such as styrene, styrene-acrylate, styrene-butadiene, acrylate, polyester and phenolic-epoxy resins, polysulphones, polyurethanes, individually or in combination, and also polyethylene and polypropylene, in or to which further ingredients, such as charge control agents, waxes or flow assistants may be present or may be added subsequently.
A further area of application of pigments of the invention is their use as colorants in powders and powder coating materials, especially triboelectrically or electrokinetically sprayed powder coating materials, which are used to coat the surfaces of articles made, for example, from metal, wood, plastic, glass, ceramic, concrete, textile material, paper or rubber (J. F. Hughes, xe2x80x9cElectrostatics Powder Coatingxe2x80x9d, Research Studies Press, John Wiley and Sons, 1984).
Powder coating resins employed are typically epoxy resins, carboxyl- and hydroxyl-containing polyester resins, polyurethane resins and acrylic resins, together with customary hardeners. Combinations of resins are also used. For example, epoxy resins are frequently employed in combination with carboxyl- and hydroxyl-containing polyester resins. Examples of typical hardener components (depending on the resin system) are acid anhydrides, imidazoles and dicyandiamide and derivatives thereof, blocked isocyanates, bisacylurethanes, phenolic and melamine resins, triglycidyl isocyanurates, oxazolines and dicarboxylic acids.
The pigments of the invention are suitable, moreover, as colorants in ink-jet inks, both aqueous and non-aqueous, and in those inks which operate in accordance with the hot-melt process.